Signal path processing bias error detector

ABSTRACT

The present invention detects, determines, and mitigates signal-path processing errors. An extracted and inverted reference signal is compared to the carrier signal produced by various functional components to determine the error introduced to that signal by functional components. After the signal has been processed by various signal-processing components, the signal can once again be compared to the inverted reference signal so that a signal-path processing bias can be determined. Using that determination, a signal modification can be initiated to substantially reduce or eliminate all signal-path processing error.

RELATED APPLICATION

The present application relates to and claims the benefit of priority toU.S. Non Provisional Patent Application No. 14/602,973 filed 22 Jan.2015 which claims the benefit of priority to Provisional PatentApplication No. 61/930,397 filed 22 Jan. 2014, which is herebyincorporated by reference in its entirety for all purposes as if fullyset forth herein.

STATEMENT REGARDING FEDERAL SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with U.S. Government support under contractHQ0147-12-C-7810 awarded by the U.S. Missile Defense Agency. TheGovernment has certain rights to this invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention relate, in general, to biasstability and more particularly, to methods and systems for detectingbias errors in a signal-processing path.

2. Relevant Background

In engineering, “bias” is the systematic deviation from a referencevalue. It is a prejudice or an amount by which the average set of valuesdeparts from a reference value. It can also be considered to be thepredicted difference on average between the measurement and the truevalue. A closely related topic in engineering is “stability.” Stabilityis the ability of a measuring instrument to retain its calibration overa long period of time. Stability, therefore, determines an instrument'sconsistency over time. Accordingly, a bias stability is whether apredicted value, different from the true value, is consistent over time.Unfortunately, it is well-known that bias errors in signal pathprocessing are unstable.

To measure the bias, one must take a long sequence of data and find theaverage value of that data. Then, when the bias value is known, one candetermine a bias stability, which is the change in the bias measurementat a different instant in time. For example, what would the bias be ifwe took data two hours from now? To measure bias stability, we need tomeasure the bias at many different points in time and see how the biaschanges during that time. But even this leaves some question unanswered:for example, how long should we average the data, and how many timesshould we measure the bias to make a valid measurement of the biasstability, and so on.

These types of errors occur in many systems, including signalprocessing. Signal processing is an enabling technology that encompassesthe fundamental theory, applications, algorithms, and implementations ofprocessing or transferring information contained in many differentphysical, symbolic, or abstract formats. These formats are broadlydesignated as signals, and use mathematical, statistical, computational,heuristic, and linguistic representations, formalisms, and techniquesfor representation, modeling, analysis, synthesis, discovery, recovery,sensing, acquisition, extraction, learning, security, or forensicanalysis. Beyond the errors introduced from a sensor of a similar datacollection device, the very path through which the signal passes canassert a certain bias to the observed data. Moreover, the bias (orpredicted difference) varies between the data's true value and itsobserved value. That means that the signal processing path bias is notstable. Therefore, a need exists to determine and account for signalprocessing path bias and changes that may occur to that bias over time.These and other deficiencies of the prior art are addressed by one ormore embodiments of the present invention.

Additional advantages and novel features of this invention shall be setforth in part in the description that follows, and in part will becomeapparent to those skilled in the art upon examination of the followingspecification or may be learned by the practice of the invention. Theadvantages of the invention may be realized and attained by means of theinstrumentalities, combinations, compositions, and methods particularlypointed out in the appended claims.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention detects, determines,and mitigates signal-path processing errors. An extracted and invertedreference signal is compared to the carrier signal produced by variousfunctional components to determine the error introduced to that signalby functional components. After the signal has been processed by varioussignal-processing components, the signal can once again be compared tothe inverted reference signal so that a signal-path processing bias canbe determined. Using that determination, a signal modification can beinitiated to substantially reduce or eliminate all signal-pathprocessing error.

The features and advantages described in this disclosure and in thefollowing detailed description are not all-inclusive. Many additionalfeatures and advantages will be apparent to one of ordinary skill in therelevant art in view of the drawings, specification, and claims hereof.Moreover, it should be noted that the language used in the specificationhas been principally selected for readability and instructional purposesand may not have been selected to delineate or circumscribe theinventive subject matter; reference to the claims is necessary todetermine such inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The aforementioned and other features and objects of the presentinvention and the manner of attaining them will become more apparent,and the invention itself will be best understood, by reference to thefollowing description of one or more embodiments taken in conjunctionwith the accompanying drawings, wherein:

FIG. 1 shows a high-level functional block diagram of a system fordetection and correction of signal-path processing bias according to oneembodiment of the present invention;

FIG. 2 shows a high-level functional block diagram of a sensor circuitembodying a system for detection and mitigation of signal-pathprocessing error according to one embodiment of the present invention;

FIG. 3 is a graphical representation of a comparison between a carriersignal and its inverse used to detect signal-path processing erroraccording to one embodiment of the present invention;

FIG. 4 is a graphical representation of change, over a period of time,of signal-path processing error as compared to error introduced by afunctional component, according to one embodiment of the presentinvention; and

FIG. 5 is a flowchart of one methodology for detecting and mitigationsignal-path processing error according to one embodiment of the presentinvention.

The Figures depict embodiments of the present invention for purposes ofillustration only. One skilled in the art will readily recognize fromthe following discussion that alternative embodiments of the structuresand methods illustrated herein may be employed without departing fromthe principles of the invention described herein.

DESCRIPTION OF THE INVENTION

Described below by way of example is a system and associated methodologyfor detecting bias errors in a signal-processing path. Signal pathprocessing is the most likely source of bias error in time spans thatexceed twenty-four hours. It is also the most likely source of error inenvironments experiencing high thermal gradients (δtT>2° C./s).

Embodiments of the present invention are hereafter described in detailwith reference to the accompanying Figures. Although the invention hasbeen described and illustrated with a certain degree of particularity,it is understood that the present disclosure has been made only by wayof example and that those skilled in the art can resort to numerouschanges in the combination and arrangement of parts without departingfrom the spirit and scope of the invention.

The following description, with reference to the accompanying drawings,is provided to assist in a comprehensive understanding of exemplaryembodiments of the present invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding, but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. Also, descriptions of well-known functions and constructionsare omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention are provided for illustration purpose only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

By the term “substantially,” it is meant that the recitedcharacteristic, parameter, or value need not be achieved exactly, butthat deviations or variations (including for example, tolerances,measurement error, measurement accuracy limitations and other factorsknown to those of skill in the art) may occur in amounts that do notpreclude the effect the characteristic was intended to provide.

Like numbers refer to like elements throughout. In the figures, thesizes of certain lines, layers, components, elements, or features may beexaggerated for clarity.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. Thus, for example, reference to “a component surface”includes reference to one or more of such surfaces.

As used herein, any reference to “one embodiment” or “an embodiment”means that a particular element, feature, structure, or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. The appearances of the phrase “in one embodiment” in variousplaces in the specification are not necessarily all referring to thesame embodiment.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having,” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements, but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the specification andrelevant art and should not be interpreted in an idealized or overlyformal sense unless expressly so defined herein. Well-known functions orconstructions may not be described in detail for brevity and/or clarity.

It will be also understood that when an element is referred to as being“on,” “attached” to, “connected” to, “coupled” with, “contacting,”“mounted” etc., another element, it can be directly on, attached to,connected to, coupled with, or contacting the other element orintervening elements may also be present. In contrast, when an elementis referred to as being, for example, “directly on,” “directly attached”to, “directly connected” to, “directly coupled” with, or “directlycontacting” another element, there are no intervening elements present.It will also be appreciated by those of skill in the art that referencesto a structure or feature that is disposed “adjacent” another featuremay have portions that overlap or underlie the adjacent feature.

Spatially relative terms, such as “under,” “below,” “lower,” “over,”“upper,” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the Figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of a device in use or operation in addition to theorientation depicted in the Figures. For example, if a device in theFigures is inverted, elements described as “under” or “beneath” otherelements or features would then be oriented “over” the other elements orfeatures. Thus, the exemplary term “under” can encompass both anorientation of “over” and “under.” The device may be otherwise oriented(rotated 90 degrees or at other orientations), and the spatiallyrelative descriptors used herein interpreted accordingly. Similarly, theterms “upwardly,” “downwardly,” “vertical,” “horizontal,” and the likeare used herein for the purpose of explanation only unless specificallyindicated otherwise.

According to one embodiment of the present invention, signal pathprocessing errors can be detected and compensated for by quicklyreversing an analog signal relative to material signal variations toidentify an offset or bias. FIG. 1 presents a high-level block diagramof a signal path processing bias error detector according to oneembodiment of the present invention. As shown, a reference signal 140 isfirst extracted from the initial input of a signal path 105. Thereafter,it is used by the detector 130 to identify signal path error. One ofreasonable skill in the relevant art will recognize that the signal path110 depicted in FIG. 1 could comprise multiple components as needed fora specific circuit. The concepts of signal-path error detection andcompensation presented herein are applicable regardless of the signalpath composition. In one embodiment of the present invention, a signalenters 105 a system, a reference signal 140 is taken, and then isreversed by a switch 145. The reserved signal is delivered to a signalbias detector that resides at or near the end of the signal path 110.

The signal 120 that exits from the signal path 110 includes variouserrors introduced by components within the path. That error can bedetected (and thereafter compensated for) by comparing it to the inverseof the signal. In this example, the signal bias detector 130 receivesthe signal from the signal path 120 and compares it to an inverse ofitself (the signal) prior to entering the signal path. If there were noerror introduced due to the signal path, the two signals would cancelthemselves out. However, any difference between the two can beattributed to the signal path. For example, if the signal entering thesignal path 105 is 0.5 volts, the reference signal 140 would be −0.5volts. If the signal 120 entering the signal bias detector 130 is 0.53volts, the detector would recognize 0.03 volts as a signal pathprocessing error. In other embodiments of the present invention, theexiting signal 150 can be adjusted back to its original value.

FIG. 2 is a high-level block diagram showing what will be recognized byone of reasonable skill in the relevant art as a signal-processing pathfor differential positional sensor electronics. While the circuitdetails of various sensor technologies and various components in thesignal path may vary, the functional blocks remain essentially the same.

In this example, the signal-processing path 200 begins with anoscillator 205. The resulting signal is then coupled with a clock 210that, in this case, divides the signal 215. A reference signal 218 isextracted from the signal path 215 and inverted using a switch 225. Theoriginal signal 215 then interfaces with a sensor network 220, which isthe portion of the signal path 200 that is comprised of the sensor heads(or coils), connecting cables (if any), and one or more passivecomponents. The elimination of errors introduced into the signal path200 by the sensor network 220 is the subject of additional applicationsand is beyond the scope of this discussion. Nonetheless, it is importantto observe that, in this example, the present invention does noteliminate or compensate for errors introduced by the sensors network,but rather eliminates or compensates additional errors and inaccuracyadded to the signal generated by the sensor network 110 from the signalpath. In other words, one or more embodiments of the present inventiondetect cumulative bias errors due to the functional blocks that followthe sensor network 110 within the signal path 100, such as ananalog-to-digital convertor and its associated input stages, voltagereferences, filters, and the like.

Consider, for example, with continued reference to FIG. 2, that one wayto measure bias in an accelerometer is to set the accelerometer on astable table or platform with its measurement axis aligned parallel withthe local gravitational vector and note the output signal value. Assumefor this example, that the accelerometer identifies an acceleration of32 f/s/s as indicated by a certain positive voltage value of +0.15 mv.Next, one simply inverts the accelerometer and again notes the outputsignal value. In this case, the acceleration is −32.1 f/s/s as indicatedby −0.155 mv, and is recorded. The bias, in this simple example, is theaverage of the two readings, or −0.0025 mv. Further assume for thisexample that −0.0025 mv represents an acceleration of −0.05 f/s/s. Thebias of the accelerometer is therefore −0.0025 mv or −0.05 f/s/s. Thisbias is, however, a combination of sensor bias and bias introduced bythe signal-processing path. Assume in this case that the bias errorintroduced by the sensor is −0.0020 mv, and the error introduced by thesignal-processing path is −0.0005 mv. Over time, the output signalvalues may change, as may their average, or in other words, their bias.Therefore, repeating this experiment at some later times will likelyyield a second, third, fourth, etc. bias measurement. Any differencebetween the results can be referred to as the accelerometer's bias erroror bias drift. Once known, this drift can be accounted for so as toprovide a better representation of what is actually transpiring.However, what remains uncertain is what portion of the error isattributed to the sensor itself or the signal path.

The type of a calibration presented above is not practical outside thelaboratory or after the accelerometer is installed in an InertialMeasurement Unit (IMU). In accordance with one embodiment of the presentinvention, a very similar test can be performed on electronic systemswithout altering the physical condition of a sensor, and can isolate theerror due to the signal path. A bias determination process caneffectively occur by inverting the signal shown connecting the sensornetwork block 220 in FIG. 2 with the signal detection and differencingblock 230.

By accomplishing this reversal very quickly relative to the motion ofthe inertial mass in the accelerometer of the sensor network 220, thenet result is exactly the same as with the physical laboratorycalibration test, but further isolates bias error due tosignal-processing from that of the sensor networks. Since the reversalof the signals is quick, the error introduced by the sensor networkremains constant. Therefore, any bias identified by the methodology ofthe present invention is isolated by the passive components associatedwith signal processing. Furthermore, this test can be performed at anytime and with the accelerometer in any position. Signals from othertypes of sensors can also be reversed in the same manner to identifysignal-processing path bias.

Consider the following example: the oscillator 205 generates a signal208 that is thereafter divided 215. Assume that the divided signal postclock 210 has a value of 0.5 mv. A reference signal 218 of 0.5 mv isextracted from the path and inverted by a switch 225. The originalsignal 215 is also supplied to the sensor network. The sensor networkproduces data embedded in the signal 222 having a value of 0.52 mv. Asignal detection and difference component 230 recognizes that thedifferences between the post sensor network signal 222 and the extractedreference signal 218 are errors attributed to the sensor network. Inthis case, the error introduced to signal by the sensor network is 0.02mv.

The signal is then filtered by a low bypass filter 240, amplified by adifferential amplifier 250, and balanced by a line driver 260. One ofreasonable skill in the relevant art will recognize that the additionalcomponents shown in the signal path of FIG. 2 are for illustrativepurposes only and that additional or different components can be addedor subtracted from the processing path without departing from the scopeof the present invention.

As the signal transcends the various components, error attributed to thesignal path is introduced to the signal. In this example, assume thatthe signal 265 exiting from the balanced line driver 260 is 0.55 mv. Thesignal-path processing bias detector 270 compares the signal 265received from balanced line driver 260 with that of the invertedreference signal 218 and the post sensor network signal 222. Since thevalue of the signal after the sensor network 220 was 0.52 mv, and 0.02mv was introduced by sensor network error, the signal-path processingbias detector 270 can determine that an additional 0.03 mv of error wasintroduced to the signal path by components after the sensor network220. In this example, the filter 240, differential amplifier 250, andbalanced line driver introduced an additional 0.3 mv of error into thesignal.

In another embodiment of the present invention. additional comparisonscan be conducted, if necessary, to identify the extent of errorintroduced to the signal-processing path by each component. For example,using the same technique, the present invention can identify that of the0.03 mv of error introduced by the filter 240, differential amplifier250, and balanced line driver 260, 0.01 mv was introduced by the filter240, 0.0025 was introduced by the differential amplifier 250, and 0.0175was introduced by the balanced line driver 260. And as one or reasonableskill in the relevant art will recognize, the same approach can bescaled to encompass other components or blocks of components.

Once the signal-processing path bias has been detected, an adjustment orcompensation can be added to the signal to effectively reduce oreliminate all signal-processing path error. Using the example above, asignal bias compensator 280 can modify the signal 265 by adding −0.03mv. The resulting signal will be 0.052, which is identical to the signal222, leaving the sensor network 220 with the added processing featuresof the filter 240, differential amplifier 250, and balanced line driver260. Thus, the signal-processing path error has been detected andeliminated.

In one version of the present invention, the process of signal pathprocessing bias detection and compensation is accomplished withdetection schemes using synchronous demodulators such as Gilbert cellsand its derivatives. It can also be accomplished, in a differentembodiment, with phase detection circuits.

By analogy, and in an over-simplification for illustrative purposes, thepresent invention is similar to measuring the voltage on your carbattery with a hand-held voltmeter and swapping the leads. If theaverage reading is not exactly zero, then your voltmeter must have anoffset error (bias).

With respect to the use of the present invention in systems that includean accelerometer, the bias test of the present invention can beperformed in less than 40 μs with 20+ bits of digital precision. In anoperational environment with highly dynamic accelerations, it may benecessary to average several readings to achieve useful data. By doingso, not only can the signal-processing path bias be accuratelydetermined and compensated, but also the dynamic nature of the bias(drift) can be understood. Thus, errors (bias) introduced by thesignal-processing path can be identified and accommodated to reduce oreliminate any signal path processing bias errors.

“Drift” is an inconsistency in bias. FIG. 3 shows a graphicalillustration of variances in data found in the signals detected by thesignal detection and differencing component 230. Over time, thedifferences in the original signal and that of the reference signal mayvary. During a period of time, t₁ 310, each signal received 320 iscompared to its inverse 330. That value, as discussed above, identifiesthe error introduced into the signal by the sensor network and thesignal path. In the example above, assume that sampling over time (t₁))has determined that the error attributed to the sensor network is 0.2 mvand 0.3 mv for the signal path.

By sampling the errors over various time intervals, an appreciation forthe signal-path processing and, in this example, sensor network errordrift can be observed. FIG. 4 presents a graphical illustration oferrors identified by the present invention over a period of time. Inthis illustration, sensor network error 430 and signal-path processingerror 410 are graphed over a period of four time intervals. Theillustration of FIG. 4 identifies that the error due to signal-pathprocessing is substantially constant while the sensor network errorappears to be increasing at a linear rate. Using information such asthis, an error mitigation protocol can be developed, as can decisionpoints for recalibration, part replacement, or periods of useful life.

FIG. 5 presents a flowchart depicting an example of a methodology thatmay be used to detect and mitigate signal-path processing error. In thefollowing description, it will be understood that each block of theflowchart illustrations, and combinations of blocks in the flowchartillustrations, can be implemented by, in part or in association with,computer program instructions. These computer program instructions maybe loaded onto a computer or other programmable apparatus to produce amachine such that the instructions execute on the computer or otherprogrammable apparatus creating a means for implementing the functionsspecified in the flowchart block or blocks. These computer programinstructions may also be stored in a computer-readable memory that candirect a computer or other programmable apparatus to function in aparticular manner such that the instructions stored in thecomputer-readable memory produce an article of manufacture includinginstruction means that implement the function specified in the flowchartblock or blocks. The computer program instructions may also be loadedonto a computer or other programmable apparatus to cause a series ofoperational steps to be performed in the computer or on the otherprogrammable apparatus to produce a computer implemented process suchthat the instructions that execute on the computer or other programmableapparatus provide steps for implementing the functions specified in theflowchart block or blocks.

Accordingly, blocks of the flowchart illustrations support combinationsof means for performing the specified functions and combinations ofsteps for performing the specified functions. It will also be understoodthat each block of the flowchart illustrations, and combinations ofblocks in the flowchart illustrations, can be implemented by specialpurpose hardware-based computer systems that perform the specifiedfunctions or steps, or combinations of special purpose hardware andcomputer instructions.

The methodology shown in FIG. 5 begins 505 with the production orgeneration of a carrier signal 510. In one embodiment of the presentinvention, an oscillator creates a signal that can then be divided by aclock. From that carrier signal, a reference signal is extracted 515 andthen inverted 520 using a switch or similar device. Concurrently, thecarrier signal is utilized 530 by one or more functional components. Afunctional component can be a sensor network or the like which can usethe carrier signal as a means to embed useful data.

Thereafter, the carrier signal and the inverted reference signal arereceived 540, in one embodiment, by a signal detection and differencingcomponent. The carrier signal and the inverted reference signal areaveraged 545 to arrive at a determination of the error imparted onto thecarrier signal by the functional component(s).

The carrier signal is processed along a signal-path 550 to modify,convert, and enhance the signal. In one embodiment of the presentinvention, components such as filters, amplifiers, and drivers modifythe signal to achieve a desired result. The carrier signal is received560 at the end of the signal path by a bias detector that once againcompares the carrier signal to the inverted reference signal todetermine 570 a cumulative error imparted onto the carrier wave sinceits generation.

Knowing the cumulative error, the signal-path processing error impartedonto the carrier signal by the signal-path processing components isdetermined 580 by subtracting the functional component error from thecumulative error. With the signal-path processing error (bias)determined, signal-path processing error mitigation 590 can occur toremove any error introduced to the carrier signal by the signal-pathcomponents 595, ending the process.

One or more embodiments of the present invention detect, determine, andmitigate signal-path processing errors. By comparing an extracted andinverted reference signal to the carrier signal produced by variousfunctional components, the error introduced to that signal can beunderstood. After the signal has been processed by various signalcomponents, the signal can once again be compared to the invertedreference signal so that a signal-path processing bias can bedetermined. Using that determination, a modification to signal can beinitiated to substantially reduce or eliminate all signal-pathprocessing error.

While the principles of the present invention in conjunction with adetermination and mitigation of signal-path processing bias have beendescribed above, it is to be clearly understood that the foregoingdescription is made only by way of example and not as a limitation tothe scope of the invention. Particularly, it is recognized that theteachings of the foregoing disclosure will suggest other modificationsto those persons skilled in the relevant art. Such modifications mayinvolve other features that are already known per se, and which may beused instead of or in addition to features already described herein.Although claims have been formulated in this application to particularcombinations of features, it should be understood that the scope of thedisclosure herein also includes any novel feature or any novelcombination of features disclosed either explicitly or implicitly, orany generalization or modification thereof which would be apparent topersons skilled in the relevant art, whether or not such relates to thesame invention as presently claimed in any claim and whether or not itmitigates any or all of the same technical problems as confronted by thepresent invention. The Applicant hereby reserves the right to formulatenew claims to such features and/or combinations of such features duringthe prosecution of the present application or of any further applicationderived therefrom.

1. (canceled)
 2. A method for determining signal-path processing bias,comprising: receiving, at one or more functional components, a firstcarrier signal wherein the first carrier signal includes a referencesignal and wherein the one or more functional components adds acomponent error to the first carrier signal forming a second carriersignal; averaging an inversion of the reference signal with the secondcarrier signal to identify the component error; processing the secondcarrier signal by one or more signal-processing components and whereinthe one or more signal processing components adds a signal processingerror to the second carrier signal forming a third carrier signal;determining a signal-path processing bias by averaging the third carriersignal with the inversion of the reference signal and thereaftersubtracting the component error.
 3. The method for detecting signal-pathprocessing bias according to claim 2, wherein the component error issensor network error.
 4. The method for detecting signal-path processingbias according to claim 2, wherein the inversion of the reference signalis accomplished by a switch.
 5. The method for detecting signal-pathprocessing bias according to claim 2, further comprising compensatingthe third carrier signal based on the signal-path processing bias. 6.The method for detecting signal-path processing bias according to claim2, further comprising monitoring the signal-path processing bias over atime interval to determine a rate of change of the signal-pathprocessing bias.
 7. The method for detecting signal-path processing biasaccording to claim 6, further comprising mitigating signal-pathprocessing bias at a predetermined time.
 8. The method for detectingsignal-path processing bias according to claim 6, further comprisingmitigating signal-path processing bias at predetermined time intervals.9. A system for signal-path processing error detection, comprising afirst carrier signal; a reference signal associated with the firstcarrier signal; one or more functional components, wherein the one ormore functional components receives the first carrier signal and acomponent error is added by the one or more functional components to thefirst carrier signal forming a second carrier signal; a signal inversioncomponent wherein the signal inversion components receives the referencesignal to form an inverted reference signal; a signal detection anddifferencing component coupled to the signal inversion component and theone or more functional components wherein the signal and differencingcomponent average the second carrier signal with the inverted referencesignal to identify the component error; one or more signal-pathprocessing components coupled to the signal detection and differencingcomponent wherein the one or more signal-path processing componentsreceives the the second carrier signal and a signal-path processor erroris added by the one or more signal-path processing components to thesecond carrier signal forming a third carrier signal; and a signal-pathbias detector coupled to the one or more signal-path processingcomponents, the signal inversion component and the signal detection anddifferencing component to identify a signal-path bias by averaging thethird carrier signal with the inverted reference signal and thereaftersubtracting the component error.
 10. The system for signal-pathprocessing error detection according to claim 9, wherein the firstcarrier signal is generated by a oscillator. 11 The system forsignal-path processing error detection according to claim 9, wherein theone or more functional components are one or more sensors.
 12. Thesystem for signal-path processing error detection according to claim 9,wherein the signal inversion component is a switch.
 13. The system forsignal-path processing error detection according to claim 9, wherein thesignal inversion component is an inverting amplifier.
 14. The system forsignal-path processing error detection according to claim 9, wherein thesignal inversion component shifts phase of the signal 180 degrees. 15.The system for signal-path processing error detection according to claim9, wherein the signal-path processing components includes a filter. 16.The system for signal-path processing error detection according to claim9, wherein the signal-path processing components includes an amplifier.17. The system for signal-path processing error detection according toclaim 9, wherein the signal-path processing component includes abalanced line driver.
 18. A method for detecting a signal-pathprocessing error, comprising: determining a first error introduced to asignal by one or more functional components; ascertaining a second errorintroduced to the signal by the one or more functional components andone or more signal-path processing components; and identifying thesignal-path processing error by subtracting the first error from thesecond error.